In general, unlike an analogue content, since a digital content can be unlimitedly copied without a loss of information, the digital content can be easily exposed to illegal copy and use. This is why a content protection technique capable of stably protecting a digital content against illegal copy and use has to be supported in order to provide a digital content service.
A digital rights management (DRM) is a total digital content protection technique capable of allowing only a legally authorized user to use a digital content. Although the DRM technically includes a security technique, a watermarking technique, a tamper resistance technique, and the like, more accurately, the DRM indicates a framework rather than technologies.
The DRM focuses on radically preventing illegal copy and use of a content. In the DRM, a digital content is transformed into encrypted data in a package form by using an encryption technique. Accordingly, although the digital content is casually obtained by a predetermined user, the digital content cannot be used without a legal authentication process.
Most legal content services provided through a wired/wireless communication network such as the Internet or mobile communication network can be executed only by DRM devices which support a DRM employed by a service provider or content provider of the corresponding content. This is due to technical and political closure properties of the DRM.
On the other hand, the technical and political closure properties of the DRM are advantageous in that the legality of the content is secured. However, there is a problem that it is limited for a user to use the content. This is because DRM device or DRM-using software in which a DRM employed by the service provider is installed has to be separately included, so that a user may use a digital content provided by a plurality of service provider. In this case, the user has to separately make a contract, a payment, an authentication, and the like. [8] The aforementioned problem deteriorates flexibility of a distribution structure of digital contents. Finally, the problem causes limitation of digital content services.
Recently, it is intended to provide a framework in which the closed DRM structures are compatible with one another. In order to allow different types of DRMs to be compatible with one another, there is required a DRM interoperable system which mediates the difference among the closed DRMs. The DRM interoperable system can be embodied by defining system resources and suggesting operation models which generate and manage the defined system resources. In addition, in order to support the DRM interoperable system, various scenarios using defined system resources and operation models have to be suggested.